Re: ti_scm_syscon driver

Oskar Holmlund via freebsd-arm <[email protected]>
Newsgroups gmane.os.freebsd.devel.arm
Message-ID <[email protected]>
Den måndag 7 september 2020 02:30:57 CEST, Thomas Skibo <[email protected]> skrev: 

Hello.

I am testing some code I have developed to provide the Zynq boards with
a real clock driver and update the other device drivers to use the clock
infrastructure.  It is also supposed to allow us to use "upstream" gnu
dts files.  But, I ran into a problem booting a GENERIC kernel on my Zybo.
The ti_scm_syscon driver, which has the "syscon" compatibility string,
grabs the zynq-slcr node before my driver.  The compatibility property
for the node in the GNU dts file is;

    compatible = "xlnx,zynq-slcr", "syscon", "simple-mfd";

I fixed the problem by having my probe routine return DEVICE_PROBE_SPECIFIC.
But, the DEVICE_PROBE(9) man page seems to say I shouldn't do this.  Also, I
see a lot of device nodes in other boards that have "syscon" along with their
more specific driver name.  Aren't they going to run into problems too if
the ti_scm_syscon driver matches them?  Should the ti_scm_syscon driver use
a lower priority return value in its probe routine?

--Thomas Skibo

_______________________________________________
[email protected] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-arm
To unsubscribe, send any mail to "[email protected]"


Hi Thomas,

I'm sorry I've caused you trouble with ti_scm_syscon.c catchall for syscon.

I will try to point out the situation from TI dts.
(head) sys/gnu/dts/arm/am33xx-l4.dtsi from line 270 the control module are defined and 286 the syscon part.
The Control module are described here
https://www.kernel.org/doc/Documentation/devicetree/bindings/arm/omap/ctrl.txt
the syscon part is not directly documented for TI its just there in the example.
(of course this exist https://www.kernel.org/doc/Documentation/devicetree/bindings/mfd/syscon.txt )

I'm glad for any suggestions to solve the issue to not interfere with other drivers.
I can test your proposal to lower the priority.
Or get TI to change syscon to something more specific in the DTS?
Maybe its better if i hardcode ti_scm.c to add the syscon child and remove the probe part from ti_scm_syscon.c?
Other suggestions?

--
Bästa Hälsningar
Oskar Holmlund
Tel 070-3220292
_______________________________________________
[email protected] mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-arm
To unsubscribe, send any mail to "[email protected]"
lmpx.com only provides a reader for public news (NNTP) servers. It is not affiliated with the servers or forums shown here and is not responsible for the content of articles, which is written by their respective authors.